A plug-in pipe fitting device, also referred to as a push-fit pipe fitting device, typically includes a base body, an elastomeric sealing ring, an annular body which can be connected to the base body and a grip ring which locks in position a pipe end inserted into the push-fit fitting device. A grip ring typically enables smooth insertion of a pipe into the fitting device but disallows the removal of the pipe from the fitting device. The grip ring of the present invention provides an improved locking mechanism that enables a continuous mechanical gripping of a pipe end, pushed into the push-fit fitting device.
Many mechanical joining applications are used in pipe systems carrying liquids having temperatures up to approximately 110° C. and higher, and pressures up to approximately 1000 psi. As well fitting devices of this type are typically used with water pipe systems but can also used with fluids of all types, including toxic and volatile chemicals. In water pipe systems, the fittings are designated to be used with no leaks for a prolonged period of time, which is often 50 years and more.
There are many types of prior art grip rings used in the industry to lock pipes in position. The most common one is using
FIG. 13 (Prior art) illustrates a prior art grip ring 10, having one or more annular saw teeth 20 and one or more slits 30 that enables reducing grip ring inner diameter when pushed inward by an external nut (not shown). US patent application 20050084327 by David Chelchowski et al provides such a grip ring, which may loosen up during a lifespan of a fitting device. The commonly used saw teeth mechanism allows the inserted pipe to slide over the gentler slope of the teeth, whereas when the pipe moves outwardly from the fitting device the teeth edge digs into the external surface of the pipe and locks the pipe in position.
There is therefore a need for and it would be advantageous to have a grip ring that locks the pipe in an increased force and increases the grip locking force when the pipe attempts to move out of the fitting device.